Manufacture of chlorhydrin



Aug. 211, 1923.

B. T. BROOKS MANUFACTURE oF CHLORHYDRIN Filed June 20, 1918.lslllllllllariililihfllllf E...

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Patented Aug. 21, i923.

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BENJAMIN T. BROOKS, OF BAYSIDE, NEW YORK, ASSIGNOR, BY MESNEASSIGNMENTS, TO CARBIDE AND CARBON CHEMICALS CORPORATION, A CORPORATIONF NEW YORK.

MANUFACTURE or CHLORHYDRIN.

Application filed .Tune 20, 1918.

To al Z wiz-0m it may concern Be it ,known that I, BENJAMIN T. BROOKS,

- a citizen of the United States, residing at Bayside, county of Queens,and State of New York, have invented certain new and useful Improvementsin Manufacture of Chlorhydrin, fully described and represented in thefollowing specification and the accompanying drawings, forming a part ofthe same.

The present invention relates to improvements in the manufacture ofchlorhydrins of unsaturated hydrocarbons.

The object of the invention is to provide a process by which suchchlorhydrins-can be produced rapidly in large quantities moreeconomically than has been possible heretofore and with an apparatusoccupying far less space for a corresponding output than has heretoforebeen possible.

lVith the above object in view, the invention consists in the featuresand details which will first be described in connection with theaccompanying drawings of an apparatus and then more particularly pointedout.

The drawing is a diagrammatic illustration of an apparatus suitable forcarrying out the present invention.

In carrying out the process in the best form, a gas comprising orconsisting of an unsaturated hydrocarbon in gaseous state, andparticularly a normally gaseous unsaturated hydrocarbon, such, forexample, as an olefin gaseous at normal temperature, is suppliedcontinuouslynto a weak a ueous solution of hypo'chlorous acid OCI),which also is continuously maintained in the zone of reaction. Thesolution also contains a dissolved salt. The reaction is carried outunder a pressure higher than atmospheric at a temperature which shouldnot be too high and which may be considered low relative to the priorpractice of making chlorhydrins. The resulting chlorhydrin is retainedin the solution at first, and the entire mixture is treated to generatemore hypochlorous acid in it, after .which it is brought into Contactwith more gaseous unsaturated hydrocarbon so as to form more chlorhydrinthereof. In this way the p roportion of the chlorhydrin 1n the solutionis gradually strengthened. But, as I have discovered, it is notadvantageous to allow so that the amount of Serial No. 240,907.

the proportion 0f chlorhydrin to become too` high, since apparently amaximum of efli-' ciency is reached, after which the increase ofstrengthof the chlorhydrin solution results in disadvantageous counterreactions of the chl-orhydrin and other materials.

Referring to the drawings, A is a vessel` constituting a reactionchamber arranged to sustain an interior pressure and to be unaffected bythe chemicals contained in it. In practice a shell of metal, andpreferably steel, is provided, this having an inert lining, such, forexample, as cementl or lead. This vessel has a liquid discharge outletconnected by a pipe B, preferably lead lined, to a storage tank C, asuitable valve I) being provided for controlling the discharge of liquidfrom the vessel A.

A gas inlet 'D, is provided near the bottom of the vessel A. This inletis arranged to deliver' gas under pressure to the vessel A, as, forexample, from a gas compressor E. The inlet pipe D is controlled by avalve d. A gas escape pipe F, connected to the top of the vessel Aserves to carry off any gases unacted upon in the chamber. A suitablevalve f, is provided in this escape pipe F, the valve being of such aconstruction that it will allow the gradual escape of such excess gas,while still maintaining the desired pressure in the vessel A. The escapepipe F discharges through a gas meter G, gas discharged may be known.

A supply pipe H is arranged to supply a solution containinghyp-ochlorous acid to the vessel. This solution is forced into thevessel A in any suitable way, as, for example, by a pump I, which pumpsfrom a suitable source of supply, as will be'explained hereinafter. Thepipe H may terminate inside the vessel A in a suitable spraying head,consisting, in the present instance, of a perforated header K. For thepurpose of insuring a proper contact of the gas and solution within thevessel A, the latter may be filled with a suitable filling material, asfor example, stone-ware filling material indicated at L. The vessel maybe provided with a pressure gauge, as indicated at M. The storage tank Chas an outlet pipe N arranged to discharge into a mixing chamber O, thepipe N being controlled by a valve n.. The mixing chamber is providedwith suitable means for agitating the materials therein. ln the presentinvention a common mechanical agitator is indicated, this comprising arotatable shaft 0, having blades o at its lower end and a pulley 02 atits upper end by which it may be driven.

The mixing vessel has an overow discharge pipe l), leading from a pointnear the upper portion of the vessel to a chlorinating vessel Q, thedischarge pipe P terminating inside the vessel Q in a sprayer p, of theusual construction. The vessel Q, is usually made of stone-ware and maybe filled with inert material such as the usual stone-ware filling, asindicated in the drawing.

To the bottom of the chlorinating vessel Q is connected a suction pipe Rleading to the pump I. supplying chlorine gas to the bottom of thevessel Q. ln the prent example the chlorine is admitted through achlorine supply pipe S provided with a flow meter T, of usuallconstruction comprising a restricted or Venturi tube t, and a U-shapedgauge tube containing a suitable liquid. The supply of chlorine may betaken from any suitable source. ln the present example, this source isindicated as a tank U containing chlorine under pressure. It isconvenient to mount this tank on an ordinary platform scales indicatedat V, so that the amount of chlorine in the tank U may be known at anytime. The tank has the usual outlet valve u, and is connected by aflexible connection such as a rubber tube, to the supply pipe S.s

The chlorinating vessel has a suitable opening at its top for the escapeof gas, as indicated at g'. Y

The operation of the apparatus in carrying out the process is asfollows:

ln irst starting, a solution of an alkali salt of a weak acid, forexample, sodium bicarbonate, is formed in the mixing chamber, as forexample, by putting into the chamber the desiredamount of sodiumbicarbonate, starting the agitator and running in water to cause theformation of a solution containing about l to 2% of bicarbonate. Thisoverflows through the pipe l) to the chlorinating vessel into which itis sprayed by the sprayer 79. As soon as the solution begins te enterthe chlorinating vessel, chlorine is admitted to the vessel through thechlorine supply pipe S.

The main reaction which takes place is represented by the equationNance, ne rer-naci noci moeS the ingredients that the resulting solutionAlso means is provided forI naasten will be a weak solution ofhypochlorous acid. ln practice the best results are obtained when theconcentration of HOCl does not quite reach 0.15 per cent. Keeping thestrength just under this limit, the yield of chlorhydrin with respect tothe chlorine and sodium bicarbonate usedis raised to about 85% of thetheoretical yield.

The solution of` h'ypochlorous acid` is pumped to the top of thereaction vessel A and sprayed into the' top of it, flowing downward overthe surfaces of the filling material. rlhe gas to be acted upon isadmitted near the' bottom of the reaction vessel through the pipe D.This gas being under pressure, produces a pressure in the reactionvessel. Vhile the pressure may be varied to a considerable extent, ithas been found in practice that a gage pressure between 75 and 90 lbs.per square inch is very suitable.

In manufacturing chlorhydrins of the oleiins, the gas employed isusually obtained by cracking petroleum products, and such gas comprisesusually some paratlins and about 30 to 50% of olefinic hydrocarbons.These yolefins generally consist mostly of ethylene and propylene inabout equal proportion, though, of course, the relative proportions varyaccording to the temperature of cracking. With such a gas the propyleneseems to be acted upon lirst by the hypochlorous acid to form propylenechlorhydrin, ethylene apparently being more resistant. Therefore, whereitis desired to form both chlorhydrins in the one reaction vessel, thegasescape valve g should be so adjusted that the surplus gas can escapeonly slowly, thus causing a. slow travel of the gas through theapparatus. The gas may be tested from time to time for olefins and theapparatus should be so controlled that only a very small percentage ofoleins appears in the escaping gas. ln practice it is possible to keepthis atabout l to 2%. ln this way both the 110 ethylene and thepropylene are acted upon by the hypo-chlorous acid to form thecorresponding chlorhydrins, which are dissolved in the liquid flowingdownward through the reaction chamber and accumulate at the bottom ofthe reaction vessel below the dias phragm therein. From time to timethis solution is discharged from the vessel to the storage tank byopening the valve The valve is then closed and the operation proceeds asbefore. @r the solution may be permitted to discharge continuously fromthe tower A by suitable regulation of the valve "When only propylene isto be acted upon, the scrape-valve g is opened wider and the gas mixtureis fed more rapidly to the reaction vessel, the rate of feed and escapebeing so regulated that the escaping gas, though containing practicallyall the ethylene of the original gas, will contain little or no propy- Amay be noted.

lene. Such escaping gas may be Jfed to another similar reaction vesseland treated in the way described above for the formation of ethylenechlorhydrin.

The solution accumulated in the storage tank may be allowed to flow intothe Vmixing chamber in a continuous st-ream where it is'stirred so as tocause it to dissolve sodium bicarbonate, whih may be added from time totime to the mixing vessel. The overflow passes to the chlorinationvessel and is then brought into contact with chlorine, so thathypochlorous acid is formed in the solution, and the mixed solution,comprising chlorhydrin, hypochlorous acid and chloride of sodium, ispassed to the reaction vessel and brought into contact with the gaseousolelin or olefins necessary to form more chlorhydrin or chlorhydrins ofthe kind or kinds in the solution.

The chlorhydrin solution is circulated and treated in the abovedescribed manner as often as may be necessary until a solution of thedesired strength of chlorhydrin is obtained. I have discovered that theefficiency of the process decreases notably after the concentration inthe solution has reached 4.5%. This decreased efficiency may be due toslow hydrolysis of the chlorhydrin, to direct action of chlorinevthereon in the chlorination chamber, or to oxidation of the chlorhydrinby free hypochlorous acid. `Whether or not these are the trueexplanations, the tact remains that any increase in concentration ot'the chlorhydrin above 4.5% should be avoided if the process is tobecarried out in the most economical manner. On the other hand, it maysometimes be desirable to carry the concentration of the chlorhydrinfurther, and the process has been carried out to produce a. 7%concentration without too great a sacrifice of eiliciency.

` I have discovered that the best results are obtained by keeping thetempera-ture of the solution on its way to the reaction vessel at about15O C. IVhile higher temperatures are permissible, I find that theeiiiciency of the process as regards chlorine and alkali salts islessened very much at temperatures higher than this.

lVhen the desired concentration of chlorhydrin has been obtained, thesolution is run from the storage tank to a suitable distillingapparatus. and distilled to recover the chlorhydrins.

In practice it is advisable to sto-p at the point just before the sodiumbicarbonate has been consumed quantitatively, and acidity thechlorhydrin solution slightly before it is distilled, becausechlorhydrin will be partly decomposed by any excess of sodiumbicarbonate at the temperature prevailing during distillation.

As examples of the process the following gases analyzed, 7% ethylene, 3%

775 gals. or about 7000 lbs. of solution containing lbs. of sodiumbicarbonate at the start was run rapidly through the chlorinatingapparatus, thence into the reaction vessel, back to the storage tank andagain through the apparatus, and so on.

hen passing through the chlorinating apparatus, chlorine was added atthe rate of about 31 lbs. per hour. This continuous circulation was keptup for 22 hours. During the lirst 15 hours 50 lbs. of sodium bicarbonatewere added per hour in the mixing chamber. By the rapid circulation ofthe solution through the chlorinating apparatus, the concentration ofthe hypochlorous acid was kept slightly below 0.15%. The gage pressuremaintained in the reaction chamber was about lbs. The oil gas employedcontained 19.5% propylene and 16.9% ethylene. The total gas consumptionwas 4,760 cubic feet. 'The total chlorine consumption was 681 lbs'. Thetotal amount of bicarbonate of soda employed was 750 lbs. The exitpropylene and 12% carbon dioxide. The remainder probably comprised gasesof the paraliine series.

The nal concentration of the chlorhydrin in the solution was 7.0%. Thetotal amount of chlorhydrin produced was about 490 lbs.

In another operation, where the process was discontinued as soon as thefinal concentration of chlorhydrin was 4%, the

amount of chlorine used was 267 lbs. and

the amount of chlorhydrin obtained was 264 lbs. In still another runwhere the process was stopped at a 4% concentration of the chlorhydrin,the amount of chlorine used was 425 lbs. and the chlorhydrin obtainedwas about 382 lbs.

In the process described sodium bicarbonate is given as the example ofan alkali salt of a weak acid. It is to be understood, however, thatother such salts may be employed. Indeed, somewhat more eflicientresults are obtained by employing borax' in place of sodium bicarbonate,or by the addition of boric acid to the sodium bicarbonate, but owing tothe. expense of such borax or' boric acid, it is necessary to recoverthese materials, and this involves a further operation, the cost ofwhich tendsto oll'set the savings dueto the use of borax or boric acid.

When boric acid is added to the reaction mixture of -sodium bicarbonate,it is added to the saturation concentration for the temperatureemployed, namely, about 3% by weight.

Further, instead of an alkali salt of a weak acid, I may use certainbasic salts capable of neutralizing hydrochloric acid, particularly suchbasic salts as magnesium oxychloride, which may be obtained by heatingMgClzHz@ or by mixing magnesium chloride and magnesium oxide orhydroxide. These function Very much in the same manner as sodiumbicarbonate, that is to say When chlorine is passed into an aqueoussolunsaturated hydrocarbons which consists in subjecting suchhydrocarbons under pressure greater than atmospheric to the action of anaqueous solution containing notdmore than 0.15 per cent of hypochlorousaci 2. The process of makingchlorhydrins of unsaturated hydrocarbonswhich consists in subjecting such hydrocarbons under pressure p greaterthan atmospheric to the action of an aqueous solution containing notmore than 0.15 per cent of hypochlorous acid, and maintaining the supplyof hypochlorous acid and of such hydrocarbon to the zone-of reaction.

3. The process of making chlorhydrins of the oleinesiwhich consists incontacting an oleine in gaseous state with a weak aqueous solutioncontaining hypochorous acid, maintaining a pressure greater thanatmospheric and a temperature of about 15 C. in the reaction zone,removing the resultant solumesses tion and lorming more hypochlorousacid in it, contacting the olenic gas With this solutionto form morechlorhydrin, removing the solution containing chlorhydrin When theconcentration of the chlorhydrin is less than 7%, and recovering thechlorhydrin therefrom. v

a. The process of making chlorhydrins of the olefines, Which consists inalternately charging a solution with hypochlorous acid and removing thehypochlorous acid by contacting an olefine with it, whereby chlorhydrinsare formed in the solution, repeating the alternation of steps to formmore chlorhydrins in the solution, and removing the chlorhydrins fromthe solution before the concentration of chlorhydrins therein eX- ceeds7%. u

-5. The process of making chlorhydrins of the olefines, which consistsin alternately charging a solution with hypochlorous acid and removingthe hypochlorous acid by contacting anv oleine With it, wherebychlorhydrins are formed in the solution, repeat ing the alternationof'steps to form more l chlorhydrins in the solution, and removing thechlorhydrins from the solution When the concentration of thechlorhydrins is about 4.5%.

, 6. rlhe processof making chlorhydrin of l unsaturated hydrocarbons,which consists 1n subjecting such hydrocarbons to the action of anaqueous solution containing not more than 0.15 per cent of hypochlorousacid.'

In testimony whereof, l have hereunto set m hand.

y BENJAMIN 'lll ERGO-KS.

